Collagen synthesis will be studied using cell-free extracts from chicken muscle. Preparations from animals at several ages, from embryonic to adult, will be examined in order to determine if protein synthesis in the embryonic muscle resembles that seen in both human and chicken muscular dystrophy. A more sensitive assay will be used to re-examine collagen synthesis in the muscle of dystrophic chickens. Other experiments will look for changes in proteins labeled by extracts from both red and white rat muscle, which has been experimentally denervated. It is expected that the pattern of protein synthesis may be comparable to that seen in dystrophic muscle. Carrier detection in Duchenne muscular dystrophy will be focused on the development of a simpler protein synthesis assay. The present assay coupled with serum creatine phosphokinase determination detects better than 90% of the carriers; however, the assay is very time consuming. Preliminary evidence shows promise for a simpler assay.